History

Patients with septic shock or systemic inflammatory response syndrome (SIRS) may have prior symptoms that suggest infection or inflammation of the respiratory tract, urinary tract, or abdominal cavity.

Patients with anaphylaxis commonly have recent iatrogenic (drug) or accidental (bee sting) exposure to an allergen and coexisting respiratory symptoms, such as wheezing and dyspnea, pruritus, or urticaria.

Staphylococcal toxic shock syndrome (TSS) is still observed most commonly in women who are menstruating, but it is also associated with recent soft-tissue injury, cutaneous infections, postpartum and cesarean delivery, wound infections, pharyngitis, and focal staphylococcal infections, such as abscess, empyema, pneumonia, and osteomyelitis. Patients often have a history of influenzalike illness (fever, arthralgias, myalgias) and a desquamating rash.

Pancreatitis may be another cause of distributive shock; expect symptoms of abdominal pain that radiate to the back, as well as nausea and vomiting. Burns also have been described as a cause of distributive shock.

Adrenal insufficiency

Adrenal insufficiency as a cause of shock should be considered in any patient with hypotension who lacks signs of infection, cardiovascular disease, or hypovolemia.

Long-term treatment with corticosteroids may result in inadequate response of the adrenal axis to stress, such as infection, surgery, or trauma, and subsequent onset or worsening of shock.

If the clinical picture is consistent with adrenal insufficiency in a person without this diagnosis, consider that this could be the first presentation of this disorder.

There is a high incidence of adrenal insufficiency in critically ill patients infected with the human immunodeficiency virus (HIV), although this incidence varies with the criteria used to diagnose adrenal insufficiency.
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Physical Examination

Cardinal features of distributive shock include the following:

Change in mental status

Heart rate - Greater than 90 beats per minute (note that heart rate elevation is not evident if the patient is on a beta blocker)

Hypotension - Systolic blood pressure less than 90 mm Hg or a reduction of 40 mm Hg from baseline

Microcirculatory abnormalities in distributive shock. Each image represents a venule (large, curved tube) and 2 capillaries (smaller tubes) and demonstrates the 2 main capillary flow patterns found in each class of microcirculatory abnormality, as they occur in distributive shock. This classification system was introduced by Elbers and Ince. Elbers P, Ince C. Bench-to-bedside review: mechanisms of critical illness—classifying microcirculatory flow abnormalities in distributive shock. Crit Care. July 19 2006;10(4):221.

Ultrasound clip demonstrating a collapsing inferior vena cava (IVC) on inspiration. A change in IVC diameter with respiration of at least 12-18% has been associated with fluid responsiveness (defined as an increase in cardiac output of >15% after a fluid bolus).

Lung ultrasound image over one lung zone showing the A-line pattern. This represents normal aeration and absence of pulmonary edema. A patient who demonstrates this pattern in conjunction with an inferior vena cava diameter that shows respirophasic variation of at least 12-18% will likely be fluid responsive.

*In cardiogenic shock due to a mechanical defect, such as mitral regurgitation, forward cardiac output is reduced, although the measured cardiac output may be unreliable. Large V waves are commonly observed in the pulmonary capillary wedge tracing in mitral regurgitation.

Disclosure: Received income in an amount equal to or greater than $250 from: Masimo, Edwards Lifesciences, Cheetah Medical<br/>Received honoraria from LiDCO Ltd for consulting; Received intellectual property rights from iNTELOMED for board membership; Received honoraria from Edwards Lifesciences for consulting; Received honoraria from Masimo, Inc for board membership.